Overhere is a simple web app that lets you listen to another Last.fm user's music stream, nearly in real time, using Spotify.

To listen along with a fellow Last.fm user, just enter in their username and click the Start listening button on Overhere. The music will start playing in Spotify (If you have problems getting this to work, try turning on scrobbling to Last.fm in Spotify's settings). The Last.fm user would have to not be blocking real-time sharing, naturally.

In our tests, there was a delay in playing songs from the other user's queue, so it's not exactly real time, but interesting and fun nonetheless.